Good to know!? C# 5.0 Key Features Reference – Part 2

Hi,

This are copy notes from the main key-points found in the MS 70-483 prep book. This might be useful to someone. A checklist of things in C#.

Also check out the exam link and the actual book:

http://www.microsoft.com/learning/en-us/exam-70-483.aspx

Exam Ref 70-483: Programming in C#

Implement multithreading and asynchronous processing

Using multiple threads can improve responsiveness and enables you to make use of multiple processors.

The Thread class can be used if you want to create your own threads explicitly. Otherwise, you can use the ThreadPool to queue work and let the runtime handle things.

A Task object encapsulates a job that needs to be executed. Tasks are the recommended way to create multithreaded code.

The Parallel class can be used to run code in parallel.

PLINQ is an extension to LINQ to run queries in parallel.

The new async and await operators can be used to write asynchronous code more easily.

Concurrent collections can be used to safely work with data in a multithreaded (concurrent access) environment.

Manage multithreading

When accessing shared data in a multithreaded environment, you need to synchronize

access to avoid errors or corrupted data.

Use the lock statement on a private object to synchronize access to a piece of code.

You can use the Interlocked class to execute simple atomic operations.

You can cancel tasks by using the CancellationTokenSource class with a

CancellationToken.

Implement program flow

Boolean expressions can use several operators: ==, !=, <, >, <=, >=, !. Those operators

can be combined together by using AND (&&), OR (||) and XOR (^).

You can use the if-else statement to execute code depending on a specific condition.

The switch statement can be used when matching a value against a couple of options.

56 Chapter 1 Manage program flow

The for loop can be used when iterating over a collection where you know the number of iterations in advance.

A while loop can be used to execute some code while a condition is true; do-while should be used when the code should be executed at least once.

foreach can be used to iterate over collections.

Jump statements such as break, goto, and continue can be used to transfer control to another line of the program.

Create and implement events and callbacks method

Delegates can be instantiated, passed around, and invoked.

Lambda expressions, also known as anonymous methods, use the => operator and

form a compact way of creating inline methods.

Events are a layer of syntactic sugar on top of delegates to easily implement the

publish-subscribe pattern.

Events can be raised only from the declaring class. Users of events can only remove

and add methods the invocation list.

You can customize events by adding a custom event accessor and by directly using the

underlying delegate type.

Implement exception handling

In the .NET Framework, you should use exceptions to report errors instead of error

codes.

Exceptions are objects that contain data about the reason for the exception.

You can use a try block with one or more catch blocks to handle different types of

exceptions.

You can use a finally block to specify code that should always run after, whether or not

an exception occurred.

You can use the throw keyword to raise an exception.

You can define your own custom exceptions when you are sure that users of your code

will handle it in a different way. Otherwise, you should use the standard .NET Framework

exceptions.

Create types

Types in C# can be a value or a reference type.

Generic types use a type parameter to make the code more flexible.

Constructors, methods, properties, fields, and indexer properties can be used to create

a type.

Optional and named parameters can be used when creating and calling methods.

Overloading methods enable a method to accept different parameters.

Extension methods can be used to add new functionality to an existing type.

Overriding enables you to redefine functionality from a base class in a derived class.

Consume types

Boxing occurs when a value type is treated as a reference type.

When converting between types, you can have an implicit or an explicit conversion.

An explicit conversion is called casting and requires special syntax.

You can create your own implicit and explicit user-defined conversions.

The .NET Framework offers several helper methods for converting types.

The dynamic keyword can be used to ease the static typing of C# and to improve

interoperability with other languages.

Enforce encapsulation

Encapsulation is important in object-oriented software. It hides internal details and

improves the usability of a type.

Data can be encapsulated with a property.

Properties can have both a get and a set accessor that can run additional code, commonly

known as getters and setters.

Types and type elements can have access modifiers to restrict accessibility.

The access modifiers are public, internal, protected, protected, internal, and private.

Explicit interface implementation can be used to hide information or to implement

interfaces with duplicate member signatures.

Create and implement a class hierarchy

Inheritance is the process in which a class is derived from another class or from an interface.

An interface specifies the public elements that a type must implement.

A class can implement multiple interfaces.

A base class can mark methods as virtual; a derived class can then override those methods to add or replace behavior.

A class can be marked as abstract so it can’t be instantiated and can function only as a base class.

A class can be marked as sealed so it can’t be inherited.

The .NET Framework offers default interfaces such as IComparable, IEnumerable, IDisposable and IUnknown.

Find, execute, and create types at runtime by using reflection

A C# assembly stores both code and metadata.

Attributes are a type of metadata that can be applied in code and queried at runtime.

Reflection is the process of inspecting the metadata of a C# application.

Through reflection you can create types, call methods, read properties, and so forth.

The CodeDOM can be used to create a compilation unit at runtime. It can be compiled or converted to a source file.

Expression trees describe a piece of code. They can be translated to something else (for example, SQL) or they can be compiled and executed.

Manage the object life cycle

Memory in C# consists of both the stack and the heap.

The heap is managed by the garbage collector.

The garbage collector frees any memory that is not referenced any more.

A finalizer is a special piece of code that’s run by the garbage collector when it removes

an object.

IDisposable can be implemented to free any unmanaged resources in a deterministic

way.

Objects implementing IDisposable can be used with a using statement to make sure

they are always freed.

A WeakReference can be used to maintain a reference to items that can be garbage

collected when necessary.

Manipulate strings

A string is an immutable reference type.

When doing a lot of string manipulations, you should use a StringBuilder.

The String class offers a lot of methods for dealing with strings like IndexOf, LastIndexOf, StartsWith, EndsWith, and Substring.

Strings can be enumerated as a collection of characters.

Formatting is the process of displaying an object as a string.

You can use format strings to change how an object is converted to a string.

You can implement formatting for your own types.

Validate application input

Validating application input is important to protect your application against both

mistakes and attacks.

Data integrity should be managed both by your application and your data store.

The Parse, TryParse, and Convert functions can be used to convert between types.

Regular expressions, or regex, can be used to match input against a specified pattern

or replace specified characters with other values.

When receiving JSON and XML files, it’s important to validate them using the built-in

types, such as with JavaScriptSerializer and XML Schemas.

Perform symmetric and asymmetric

encryption

An asymmetric algorithm uses a public and private key that are mathematically linked.

Hashing is the process of converting a large amount of data to a smaller hash code.

Digital certificates can be used to verify the authenticity of an author.

CAS are used to restrict the resources and operations an application can access and

execute.

System.Security.SecureString can be used to keep sensitive string data in memory.

Manage assemblies

An assembly is a compiled unit of code that contains metadata.

An assembly can be strongly signed to make sure that no one can tamper with the content.

Signed assemblies can be put in the GAC.

An assembly can be versioned, and applications will use the assembly version they were developed with. It’s possible to use configuration files to change these bindings.

A WinMD assembly is a special type of assembly that is used by WinRT to map non-native languages to the native WinRT components.

Debug an application

Visual Studio build configurations can be used to configure the compiler.

A debug build outputs a nonoptimized version of the code that contains extra instructions

to help debugging.

A release build outputs optimized code that can be deployed to a production

environment.

Compiler directives can be used to give extra instructions to the compiler. You can use

them, for example, to include code only in certain build configurations or to suppress

certain warnings.

A program database (PDB) file contains extra information that is required when debugging

an application.

Implement diagnostics in an application

Logging and tracing are important to monitor an application that is in production and

should be implemented right from the start.

You can use the Debug and TraceSource classes to log and trace messages. By configuring

different listeners, you can configure your application to know which data to send

where.

When you are experiencing performance problems, you can profile your application to

find the root cause and fix it.

Performance counters can be used to constantly monitor the health of your applications.

Perform I/O operations

You can work with drives by using Drive and DriveInfo.

For folders, you can use Directory and DirectoryInfo.

File and FileInfo offer methods to work with files.

The static Path class can help you in creating and parsing file paths.

Streams are an abstract way of working with a series of bytes.

There are many Stream implementations for dealing with files, network operations,

and any other types of I/O.

Remember that the file system can be accessed and changed by multiple users at the

same time. You need to keep this in mind when creating reliable applications.

When performing network requests, you can use the WebRequest and WebResponse

classes from the System.Net namespace.

Asynchronous I/O can help you create a better user experience and a more scalable

application.

Consume data

ADO.NET uses a provider model that enables you to connect to different types of

databases.

You use a DbConnection object to create a connection to a database.

You can execute queries that create, update, read, and delete (CRUD) data from a

database.

When creating queries it’s important to use parameterized queries so you avoid SQL

injection.

Objective 4.3: Query and manipulate data and objects by using LINQ CHAPTER 4 291

You can consume a web service from your application by creating a proxy for it.

You can work with XML by using the XmlReader, XmlWriter, XPathNavigator, and XmlDocument classes.

Query and manipulate data and objects by using LINQ

LINQ, which stands for Language Integrated Query, is a uniform way of writing queries

against multiple data sources.

Important language features when working with LINQ queries are implicit typing, object

initialization syntax, lambdas, extension methods, and anonymous types.

You can use LINQ with a method-based syntax and the query syntax.

LINQ queries are deferred-execution, which means that the query executes when it is

first iterated.

You can use LINQ to XML to query, create, and update XML.

Serialize and deserialize data

Serialization is the process of transforming an object to a flat file or a series of bytes.

Deserialization takes a series of bytes or a flat file and transforms it into an object.

XML serialization can be done by using the XmlSerializer.

You can use special attributes to configure the XmlSerializer.

Binary serialization can be done by using the BinaryFormatter class.

WCF uses another type of serialization that is performed by the DataContractSerializer.

JSON is a compact text format that can be created by using the DataContractJsonSerializer.

Store data in and retrieve data from collections

The .NET Framework offers both generic and nongeneric collections. When possible,

you should use the generic version.

Array is the most basic type to store a number of items. It has a fixed size.

List is a collection that can grow when needed. It’s the most-used collection.

Dictionary stores and accesses items using key/value pairs.

HashSet stores unique items and offers set operations that can be used on them.

A Queue is a first-in, first-out (FIFO) collection.

A Stack is a first-in, last-out (FILO) collection.

You can create a custom collection by inheriting from a collection class or inheriting

from one of the collection interfaces.

Good to know!? C# 5.0 Key Features Reference – Part 1

Hi here is my reference links to C# 5.0. hope it helps someone!! 🙂

Manage program flow – Multithreading, asynchronous processing, events and callbacks, exception handling
Asynchronous Programming with Async and Await (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/vstudio/hh191443.aspx
C# Operators	http://msdn.microsoft.com/en-us/library/6a71f45d.aspx
CancellationTokenSource Class	http://msdn.microsoft.com/en-us/library/system.threading.cancellationtokensource.aspx
Covariance and contravariance	http://blogs.msdn.com/b/ericlippert/archive/tags/covariance+and+contravariance/
Delegate.GetInvocationList Method	http://msdn.microsoft.com/en-us/library/system.delegate.getinvocationlist.aspx
Exceptions and Exception Handling (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/ms173160.aspx
Flow Control	http://msdn.microsoft.com/en-us/library/hh147286%28v=vs.88%29.aspx
Interlocked Methods	http://msdn.microsoft.com/en-us/library/System.Threading.Interlocked_methods.aspx
Jump Statements	http://msdn.microsoft.com/en-us/library/d96yfwee.aspx
Lambda Expressions (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/vstudio/bb397687.aspx
lock Statement (C# Reference)	http://msdn.microsoft.com/en-us/library/c5kehkcz.aspx
Parallel LINQ (PLINQ)	http://msdn.microsoft.com/en-us/library/dd460688.aspx
System.Collections.Concurrent Namespace	http://msdn.microsoft.com/en-us/library/system.collections.concurrent.aspx
System.Threading.Tasks Namespace	http://msdn.microsoft.com/en-us/library/system.threading.tasks.aspx
Thread Class	http://msdn.microsoft.com/en-us/library/system.threading.thread.aspx
ThreadLocal<T> Class	http://msdn.microsoft.com/en-us/library/dd642243.aspx
ThreadPool Class	http://msdn.microsoft.com/en-us/library/system.threading.threadpool.aspx
Using Delegates (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/ms173171%28v=vs.90%29.aspx
Volatile Class	http://msdn.microsoft.com/en-us/library/system.threading.volatile.aspx
Types – Create types, Consume types, encapsulation, class hierarchy, reflection, string/text manipulation
Abstract and Sealed Classes and Class Members (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/ms173150.aspx
Access Modifiers (C# Reference)	http://msdn.microsoft.com/en-us/library/wxh6fsc7.aspx
Anonymous Methods (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/0yw3tz5k.aspx
Attributes (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/z0w1kczw.aspx
Basic String Operations	http://msdn.microsoft.com/en-us/library/a292he7t.aspx
Best Practices for Using Strings in the .NET Framework	http://msdn.microsoft.com/en-us/library/dd465121.aspx
C# – Understanding The NET Garbage Collector	http://www.csharphelp.com/2010/02/c-understandin-the-garbage-collector/
Constructor Design	http://msdn.microsoft.com/en-us/library/vstudio/ms229060(v=vs.100).aspx
CultureInfo Class	http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.aspx
Enumeration Types (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/vstudio/cc138362.aspx
ExceptionDispatchInfo Class	http://msdn.microsoft.com/en-us/library/system.runtime.exceptionservices.exceptiondispatchinfo.aspx
Expression Trees (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/bb397951.aspx
Extension Methods (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/vstudio/bb383977.aspx
Finalize Methods and Destructors	http://msdn.microsoft.com/en-us/library/0s71x931.aspx
Generics (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/512aeb7t.aspx
IDisposable Interface	http://msdn.microsoft.com/en-us/library/system.idisposable.aspx
Immutability in C# Part One: Kinds of Immutability	http://blogs.msdn.com/b/ericlippert/archive/2007/11/13/immutability-in-c-part-one-kinds-of-immutability.aspx
Interfaces (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/vstudio/ms173156.aspx
IUnknown interface	http://msdn.microsoft.com/en-us/library/windows/desktop/ms680509%28v=vs.85%29.aspx
Managed Extensibility Framework (MEF)	http://msdn.microsoft.com/en-us/library/dd460648.aspx
Operator Keywords (C# Reference)	http://msdn.microsoft.com/en-us/library/bewds7kc%28v=vs.90%29.aspx
Properties (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/x9fsa0sw.aspx
The Big Ball of Mud and Other Architectural Disasters	http://www.codinghorror.com/blog/2007/11/the-big-ball-of-mud-and-other-architectural-disasters.html
Types (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/vstudio/ms173104.aspx
unsafe (C# Reference)	http://msdn.microsoft.com/en-us/library/chfa2zb8.aspx
Using Conversion Operators (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/85w54y0a.aspx
using Statement	http://msdn.microsoft.com/en-us/library/yh598w02.aspx
Using the CodeDOM	http://msdn.microsoft.com/en-us/library/y2k85ax6.aspx
Using the StringBuilder Class	http://msdn.microsoft.com/en-us/library/2839d5h5.aspx
Using Type dynamic (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/dd264736.aspx
Walkthrough: Creating and Using Dynamic Objects (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/ee461504.aspx
WeakReference Class	http://msdn.microsoft.com/en-us/library/system.weakreference.aspx
virtual (C# Reference)	http://msdn.microsoft.com/en-us/library/9fkccyh4.aspx
Application management and development and security – Validation, encryption, assemblies, debugging, diagnostics
.NET Framework Cryptography Model	http://msdn.microsoft.com/en-us/library/0ss79b2x.aspx
.NET Framework Cryptography Model	http://msdn.microsoft.com/en-us/library/0ss79b2x.aspx
.NET Framework Regular Expressions	http://msdn.microsoft.com/en-us/library/hs600312.aspx
Analyzing Application Performance by Using Profiling Tools	http://msdn.microsoft.com/en-us/library/z9z62c29.aspx
Authenticode	http://technet.microsoft.com/en-us/library/cc750035.aspx
Beginners Guide to Performance Profiling	http://msdn.microsoft.com/en-us/library/ms182372.aspx
C# Preprocessor Directives	http://msdn.microsoft.com/en-us/library/ed8yd1ha.aspx
Code Access Security	http://msdn.microsoft.com/en-us/library/930b76w0%28v=vs.90%29.aspx
Conditional (C# Programming Guide)	http://msdn.microsoft.com/en-us/library/4xssyw96%28v=vs.90%29.aspx
Debug Class	http://msdn.microsoft.com/en-us/library/system.diagnostics.debug.aspx
Debugger Roadmap	http://msdn.microsoft.com/en-us/library/k0k771bt.aspx
Debugging, Tracing, and Profiling	http://msdn.microsoft.com/en-us/library/7fe0dd2y.aspx
EventLog Class	http://msdn.microsoft.com/en-us/library/system.diagnostics.eventlog.aspx
Gacutil.exe (Global Assembly Cache Tool)	http://msdn.microsoft.com/en-us/library/ex0ss12c.aspx
JavaScriptSerializer Class	http://msdn.microsoft.com/en-us/library/system.web.script.serialization.javascriptserializer.aspx
Makecert.exe (Certificate Creation Tool)	http://msdn.microsoft.com/en-us/library/bfsktky3%28v=vs.110%29.aspx
Object.GetHashCode Method	http://msdn.microsoft.com/en-us/library/system.object.gethashcode%28v=vs.110%29.aspx
Parsing Strings	http://msdn.microsoft.com/en-us/library/b4w53z0y.aspx
PDB Files (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/ms241903%28v=vs.90%29.aspx
PerformanceCounter Class	http://msdn.microsoft.com/en-us/library/system.diagnostics.performancecounter.aspx
Regular Expression Language – Quick Reference	http://msdn.microsoft.com/en-us/library/az24scfc.aspx
Runtime Profiling	http://msdn.microsoft.com/en-us/library/w4bz2147.aspx
SecureString Class	http://msdn.microsoft.com/en-us/library/system.security.securestring.aspx
Sn.exe (Strong Name Tool)	http://msdn.microsoft.com/en-us/library/k5b5tt23.aspx
Step 1: Examining the Configuration Files	http://msdn.microsoft.com/en-us/library/8f6988ab.aspx
Stopwatch Class	http://msdn.microsoft.com/en-us/library/system.diagnostics.stopwatch.aspx
Symbol Server and Symbol Stores	http://msdn.microsoft.com/en-us/library/ms680693%28VS.85%29.aspx
System.ComponentModel.DataAnnotations Namespace	http://msdn.microsoft.com/en-us/library/system.componentmodel.dataannotations.aspx
System.Diagnostics Namespace	http://msdn.microsoft.com/en-us/library/system.diagnostics.aspx
TraceSource Class	http://msdn.microsoft.com/en-us/library/system.diagnostics.tracesource.aspx
Using DebuggerDisplay Attribute	http://msdn.microsoft.com/en-us/library/x810d419.aspx
XML Schema Definition Tool (Xsd.exe)	http://msdn.microsoft.com/en-us/library/x6c1kb0s.aspx
Data access and manipulation – I/O operations, consume data, LINQ data manipulation, serialization, collections
101 LINQ Samples	http://code.msdn.microsoft.com/101-LINQ-Samples-3fb9811b
ADO.NET Architecture	http://msdn.microsoft.com/en-us/library/27y4ybxw.aspx
ADO.NET DataSets	http://msdn.microsoft.com/en-us/library/zb0sdh0b.aspx
Arrays Tutorial	http://msdn.microsoft.com/en-us/library/aa288453%28v=vs.71%29.aspx
BinaryFormatter Class	http://msdn.microsoft.com/en-us/library/system.runtime.serialization.formatters.binary.binaryformatter.aspx
Collections (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/ybcx56wz.aspx
Collections and Data Structures	http://msdn.microsoft.com/en-us/library/7y3x785f.aspx
ConfigurationManager Class	http://msdn.microsoft.com/en-us/library/system.configuration.configurationmanager.aspx
DataContractSerializer Class	http://msdn.microsoft.com/en-us/library/system.runtime.serialization.datacontractserializer.aspx
DataContractSerializer Sample	http://msdn.microsoft.com/en-us/library/ms752244.aspx
DbConnection, DbCommand and DbException	http://msdn.microsoft.com/en-us/library/9hy8csk1.aspx
DbConnectionStringBuilder Class	http://msdn.microsoft.com/en-us/library/system.data.common.dbconnectionstringbuilder.aspx
Directory Class	http://msdn.microsoft.com/en-us/library/system.io.directory.aspx
DirectorySecurity Class	http://msdn.microsoft.com/en-us/library/system.security.accesscontrol.directorysecurity.aspx
DriveInfo Class	http://msdn.microsoft.com/en-us/library/system.io.driveinfo.aspx
Encoding Class	http://msdn.microsoft.com/en-us/library/system.text.encoding.aspx
Entity Framework	http://msdn.microsoft.com/en-us/data/ef.aspx
Examples of XML Serialization	http://msdn.microsoft.com/en-us/library/58a18dwa.aspx
File Class	http://msdn.microsoft.com/en-us/library/system.io.file.aspx
FileInfo Class	http://msdn.microsoft.com/en-us/library/system.io.fileinfo.aspx
FileStream Class	http://msdn.microsoft.com/en-us/library/system.io.filestream.aspx
Getting Started with LINQ in C#	http://msdn.microsoft.com/en-us/library/bb397933.aspx
How to: Extend the Async Walkthrough by Using Task.WhenAll (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/vstudio/hh556530.aspx
How to: Parse XML with XmlReader	http://msdn.microsoft.com/en-us/library/cc189056%28v=vs.95%29.aspx
HttpClient Class	http://msdn.microsoft.com/en-us/library/system.net.http.httpclient.aspx
Implementing an Implicit Transaction using Transaction Scope	http://msdn.microsoft.com/en-us/library/ee818746.aspx
MemoryStream Class	http://msdn.microsoft.com/en-us/library/system.io.memorystream.aspx
NonSerializedAttribute Class	http://msdn.microsoft.com/en-us/library/system.nonserializedattribute.aspx
Parameters and Execution Plan Reuse	http://msdn.microsoft.com/en-us/library/ms175580.aspx
Path Class	http://msdn.microsoft.com/en-us/library/system.io.path.aspx
Retrieving and Modifying Data in ADO.NET	http://msdn.microsoft.com/en-us/library/ms254937.aspx
Serialization (C# and Visual Basic)	http://msdn.microsoft.com/en-us/library/vstudio/ms233843.aspx
SQL Injection	http://msdn.microsoft.com/en-us/library/ms161953%28v=sql.105%29.aspx
SqlCommand Class	http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.aspx
SqlConnection Class	http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.aspx
SqlDataReader Class	http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqldatareader.aspx
StreamReader Class	http://msdn.microsoft.com/en-us/library/system.io.streamreader.aspx
StreamWriter Class	http://msdn.microsoft.com/en-us/library/system.io.streamwriter.aspx
System.IO.Compression Namespace	http://msdn.microsoft.com/en-us/library/system.io.compression.aspx
System.Net Namespace	http://msdn.microsoft.com/en-us/library/system.net.aspx
Using Data Contracts	http://msdn.microsoft.com/en-us/library/ms733127.aspx
Using the DbContext API	http://msdn.microsoft.com/en-us/data/gg192989%28v=msdn.10%29.aspx
var (C# Reference)	http://msdn.microsoft.com/en-us/library/bb383973.aspx
Web.config Transformation Syntax for Web Project Deployment Using Visual Studio	http://msdn.microsoft.com/en-us/library/dd465326.aspx
WebRequest Class	http://msdn.microsoft.com/en-us/library/system.net.webrequest.aspx
WebResponse Class	http://msdn.microsoft.com/en-us/library/system.net.webresponse.aspx
What Is Windows Communication Foundation	http://msdn.microsoft.com/en-us/library/ms731082.aspx
XML Standards Reference	http://msdn.microsoft.com/en-us/library/ms256177.aspx
XmlAttributes.XmlArray Property	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlattributes.xmlarray.aspx
XmlAttributes.XmlArrayItems Property	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlattributes.xmlarrayitems.aspx
XmlAttributes.XmlAttribute Property	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlattributes.xmlattribute.aspx
XmlAttributes.XmlElements Property	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlattributes.xmlelements.aspx
XmlAttributes.XmlIgnore Property	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlattributes.xmlignore.aspx
XmlDocument	http://msdn.microsoft.com/en-us/library/system.xml.xmldocument.aspx
XmlReader	http://msdn.microsoft.com/en-us/library/system.xml.xmlreader.aspx
XmlSerializer Class	http://msdn.microsoft.com/en-us/library/system.xml.serialization.xmlserializer.aspx
XmlWriter	http://msdn.microsoft.com/en-us/library/system.xml.xmlwriter.aspx
XPathNavigator	http://msdn.microsoft.com/en-us/library/system.xml.xpath.xpathnavigator.aspx

Other important links:

ENTITY FRAMEWORK	http://msdn.microsoft.com/en-us/data/ef.aspx
Visual Studio Plugins	http://www.nuget.org/
Database ConnectionStrings	http://www.connectionstrings.com/
Json.NET	http://json.codeplex.com/
LINQPad	http://www.linqpad.net/

Lost files in Sharepoint Recycle Bin that can not be restored

This time I am writing a post about a problem that a client of mine had.

The problem is rather simple BUT required allot of time and energy to fix the problem or rather in my case to recover the items:

The client at some point by someone deleted files which ended up in the recycle bin. Later the client wanted to restore these files BUT was unable to. Sharepoint was telling that the restore operation failed even though you where able to clearly see that the files where available to restore in the Recycle bin of the site.

NOTICE: Before you start to try any of the things written in this post take notice TO NOT DO these things in you client product/live environment. If you chose to do so you will cause your client to lose their MS support. MS does not support manipulation of the content databases directly to SQL Server. So take a database backup, restore it in a test or development environment and fix you problem there.

NOTICE: Use this code at your own risk. The code does some crazy stuff directly to SharePoint content database. I will not take any responsibility on anything that you do with the application and/or any part of it and it’s code.

Here are the steps which I ended up taking and a more detailed explanation on them:

1. Trying to restore the items through the object model
2. Investigating the Sharepoint content database
3. Trying to restore the files by fixing content database Recycle Bin table missing information in the files
4. Trying to recover the files directly from the AllDocsStream table

Lets start from the first item and advance from there:

1. Trying to restore the items through the object model

This is basically the same as the UI BUT I decided to give it a quick try since nothing from the UI worked and sometimes you can do things through code that you can not do through the UI.

Long story short the object model did not offer much help and any restore operation failed again or nothing happened. For this a created a forms application(code is included at the end of this post).

Here is how the final version of the application looks like: 

In this first step I create the functionality in the “Blue” area. These where the object model fixes which did not help.

There basic functionality are provided which are in the “Blue” area:

1. Restore the selected items from recycle bin
2. Delete selected items
3. And move them to the Site Collection Recycle Bin

2. Investigating the Sharepoint content database

At this point because the object model and the UI did not do what they are supposed to I simply gave up on using the “preferred” way of Microsoft and went directly into the content database. My first destination was the “Recycle Bin” table.

After a few moments of careful examination of the clients content database table I noticed that the documents that can not be restored have 4 table fields which are null while other data row in the table all have data in them.

The fields which where null where:

1. ListId
2. ListItemId
3. AuthorId
4. ListDirName

So I decided to create a code that would restore the missing values. I decided that the AuthorId and ListItemId would be defined by me during the code(since they could be anything any existing user and any integer number that is large enough not to conflict with existing ID enumeration in the target list) and the ListId and ListDirName are to be retrieved through the object model. This had to be done by retrieving the values of the following fields WebId, SiteId and DirName. In the code used these values to get the site, web and the list. After I got the list it was easy to just update the table with the list ID and the rootfolder ServerRelative URL into the ListDirName field.

You can find the code for this in the button named: “Repair Recycle Bin Items(DB)”

3. Trying to restore the files by fixing content database Recycle Bin table missing information in the files

Unfortunately what I did in step two was not enough because the sites and lists did not exist anymore for these deleted files that needed to be restored from the bin.

The next step was to try to update the following tables so that the document/file would be restored to a different web and list that actually exists.

I had to make modifications to the following tables:

1. AllDocs = Data regarding the file/document itself, where it is, it’s parent, state etc
   
2. AllDocStreams = The actual binary data of the file
3. RecycleBin = The data of a deleted file that has ended up in the recycle bin

By retrieving the DocId value from RecycleBin table from a file that can not be restored you can correlate to the documents information in the AllDocs and AllDocStream.

This step is very complex and I due to time constraints I did not get it to work properly. Some piece of data was missing to get the file restored to another location. I managed to get the file restored BUT while the list showed that it had files in it you could not access the file. So something was missing from somewhere.

You can check the code for this in the button: “Repair Recycle Bin items(DB) to inserted URL”

4. Trying to recover the files directly from the AllDocsStream table

Finally the last step was to go directly into the AllDocsStream with ADO .NET, read the binary data, retrieve the documents real name from the RecycleBin table and write that data into the hard drive.

This was SUCCESSFUL!!! It worked like a charm and the client was happy to get their files restored.

In the AllDocsStrems table the most important field is the “Content” field. This is the actual binary data that you need to retrieve and use it to write it into your hard drive.

From the RecycleBin table you need the value from the LeafName field.

Using these two piece of information you can reconstruct the file.

Here is the code that solved my problem, you can find it behind the button: “Recover files from DB”

            

String connectionString = ConfigurationSettings.AppSettings[“DBConnectionString”];

            SqlDataReader rdr = null;

            this.textBox2.Text += “Opening connection to DB”;

            using (SqlConnection connection = new SqlConnection(connectionString))

            {

                connection.Open();

                this.textBox2.Text += “Connection opened”;

                List<RecycleBinDBItem> items = new List<RecycleBinDBItem>();

                try

                {

                    // Get all such items which can not be restored properly from the UI or by object model

                    SqlCommand cmd = new SqlCommand(“SELECT * FROM RecycleBin WHERE ListDirName IS NULL”, connection);

 

                    rdr = cmd.ExecuteReader();

                    this.textBox2.Text += “Select clause executed”;

 

                    while (rdr.Read())

                    {

                        this.textBox2.Text += “Reading line: \n”;

                        this.textBox2.Text += rdr[“DirName”].ToString();

                        items.Add(new RecycleBinDBItem(rdr[“DocId”].ToString(), rdr[“LeafName”].ToString()));

                    }

                }

                finally

                {

                    // close the reader

                    if (rdr != null)

                    {

                        rdr.Close();

                    }

                    int itemIDCounter = 5000;

                    int authorID = 1;

                    // Loop through every recycle bin items that is missing needed field data from the RecycleBin table to be restored properly

                    foreach (RecycleBinDBItem item in items)

                    {

                        try

                        {

                            SqlCommand cmd = new SqlCommand(String.Format(“SELECT Content FROM AllDocStreams WHERE Id = ‘{0}'”, item.docID ), connection);

 

                            // 2. Call Execute reader to get query results

                            byte [] bArray = (byte[])cmd.ExecuteScalar();

                            // Craete the file and write the binary data from the Database

                            FileStream fs = File.Create(item.fileName, (int)bArray.Length);

                            fs.Write(bArray, 0, bArray.Length);

                            fs.Flush();

                            fs.Close();

                        }

                        catch (SqlException sqlex)

                        {

                            this.textBox2.Text += sqlex.Message + ” #######\n” + sqlex.StackTrace;

                        }

                        catch (Exception ex)

                        {

                            this.textBox2.Text += ex.Message + ” #######\n” + ex.StackTrace;

                        }

                        finally

                        {

                            if (rdr != null)

                            {

                                rdr.Close();

                            }

                        }

                    }

                }

            }

            this.textBox2.Text += “DB operations done!”;

Final words;

Hope this might help someone else who is suffering from this problem. The application and it’s code is not the prettiest BUT I did what I could in the time that was given to me and also what the client is ready to spend to solve this problem. It’s only a tool and should be treated as such.

FINAL NOTICE: Use this code at your own risk. The code does some crazy stuff directly to SharePoint content database. I will not take any responsibility on anything that you do with the application and/or any part of it and it’s code.

Check out the CodePlex Project for the code:

https://recyclebinrestoreapp.codeplex.com/

Resources: Security

SQL Injection Attacks by Example SQL Injection Cheat Sheet

SQL Injection Cheat Sheet